Cartridge case

Claim 1

A CARTRIDGE CASE FOR PROPELLANT USE COMPRISING, A BASE MEMBER HAVING A SUBSTANTIALLY CIRCULAR PERIPHERAL PORTION AND A SUBSTANTIALLY PLANAR TRAVERSE SURFACE EXTENDING INWARDLY OF SAID PERIPHERAL PORTION, SAID TRANSVERSE SURFACE HAVING A DOVETAIL SHAPED ANNULAR RECESS; A SUBSTANTIALLY CYLINDRICAL SHEET METAL BODY HAVING ONE MARGINAL END PORTION FORMED WITH A REVERSE OR RETURN BEND EXTENDING INWARDLY OF AN JUXTAPOSITIONED TO SAID MARGINAL END PORTION; MEANS SOLELY ON SAID BODY SEALINGLY INTERLOCKING OPPOSED LONGITUDINAL MARGINAL EDGES OF SAID CYLINDRICAL BODY, SAID MEANS INCLUDING AN INWARDLY DIRECTED RETURN BEND FORMED ALONG ONE OF SAID EDGES WITH A LONGITUDINAL POCKET THEREBETWEEN, AN INWARDLY DIRECTED OFFSET PROVIDED AS THE OTHER MARGINAL EDGE AND HAVING AN OUTWARDLY DIRECTED RETURN BEND THEREALONG WITH A LONGITUDINAL POCKET THEREBETWEEN, EACH OF SAID MARGINAL EDGE RETURN BENDS EXTENDING SUBSTANTIALLY THE FULL LENGTH OF SAID CYLINDER INTO THE POCKET OF THE OTHER MARGINAL EDGE WITH A LATERAL EXTENT LESS THAN THAT OF SAID OFFSET; AND MEANS SEALINGLY SECURING THE OUTERMOST EXTREMITY OF SAID MARGINAL END PORTION AND ITS CORRESPONDING RETURN BEND PORTION TO SAID BASE MEMBER ADJACENT THE PERIPHERY OF SAID TRANSVERSE SURFACE, SAID SECURING MEANS INCLUDING A COLLAR HAVING A BIFURCATED LEG PORTION ENGAGED WITHIN AND SUBSTANTIALLY FILLING SAID RECESS AND A RING LEG IN ENGAGEMENT WITH THE RETURN BEND OF SAID MARGINAL END PORTION; SO CONSTRUCTED AND ARRANGED THAT VOIDS MAY BE FORMED ALONG THE BASE OF SAID POCKETS UNDER NORMAL PRESSURE CONDITIONS WHICH WILL ALLOW FOR EXPANSION AND CONTRACTION OF SAID BODY UNDER OPERATIONAL PRESSURE DEVIATIONS.